[SIPForum-discussion] VAD and CNG

[Nikos Leontsinis]

The RTCP sender and receiver reports (see Section 6.4 rfc 3550) can
describe one timing and sequence number space per SSRC. If we turn on
vad during silence no packets are transmitted across the rtp path
hence the receiving part knows that there is no speech and no packet
loss will be reported. I guess these conditions are enough to activate
the CNG.


/nikos



On 29 September 2011 08:04, isshed <isshed.sip at gmail.com> wrote:

>
>   VAD is voice activity detection whenever it detects the silence it
> notifies the CNG module then CNG module generate the comfort Noise packets
> (SID) and because these CNG packets are not natural so depending upon the
> background noise DTX i.e discontinuos Transmission module notifies the CNG
> module to incorporate some changes in  the SID packets.
>
> Thanks
>
> On Wed, Sep 28, 2011 at 7:28 PM, Raghul Prasanna <raghul82 at yahoo.co.uk>wrote:
>
>>   Hello all,
>>
>> If we turn on VAD, RTP wont be sent during silence period saving
>> bandwidth.
>>
>> How does it know that there is no speech, when there is background noise?
>>
>> Say if somehow the device recognised silence, who will generate CNG is
>> generated locally by the other end at regular intervals? Please explain.
>>
>> Thanks
>> Prasanna
>>
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Nikos Leontsinis
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